github.com/core-coin/go-core/v2@v2.1.9/consensus/cryptore/consensus.go

// Copyright 2023 by the Authors
// This file is part of the go-core library.
//
// The go-core library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-core library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-core library. If not, see <http://www.gnu.org/licenses/>.

package cryptore

import (
	"errors"
	"fmt"
	"math/big"
	"runtime"
	"time"

	"github.com/core-coin/go-randomy"

	"github.com/core-coin/go-core/v2/common"
	"github.com/core-coin/go-core/v2/consensus"
	"github.com/core-coin/go-core/v2/core/state"
	"github.com/core-coin/go-core/v2/core/types"
	"github.com/core-coin/go-core/v2/params"
	"github.com/core-coin/go-core/v2/rlp"
	"github.com/core-coin/go-core/v2/trie"

	mapset "github.com/deckarep/golang-set"
	"golang.org/x/crypto/sha3"
)

// Cryptore proof-of-work protocol constants.
var (
	BlockReward            = big.NewInt(5e+18) // Block reward in ore for successfully mining a block
	maxUncles              = 2                 // Maximum number of uncles allowed in a single block
	allowedFutureBlockTime = 8 * time.Second   // Max time from current time allowed for blocks, before they're considered future blocks

	calcDifficulty = makeDifficultyCalculator()
)

// Various error messages to mark blocks invalid. These should be private to
// prevent engine specific errors from being referenced in the remainder of the
// codebase, inherently breaking if the engine is swapped out. Please put common
// error types into the consensus package.
var (
	errOlderBlockTime    = errors.New("timestamp older than parent")
	errTooManyUncles     = errors.New("too many uncles")
	errDuplicateUncle    = errors.New("duplicate uncle")
	errUncleIsAncestor   = errors.New("uncle is ancestor")
	errDanglingUncle     = errors.New("uncle's parent is not ancestor")
	errInvalidDifficulty = errors.New("non-positive difficulty")
	errInvalidPoW        = errors.New("invalid proof-of-work")
)

// Author implements consensus.Engine, returning the header's coinbase as the
// proof-of-work verified author of the block.
func (cryptore *Cryptore) Author(header *types.Header) (common.Address, error) {
	return header.Coinbase, nil
}

// VerifyHeader checks whether a header conforms to the consensus rules of the
// stock Core cryptore engine.
func (cryptore *Cryptore) VerifyHeader(chain consensus.ChainHeaderReader, header *types.Header, seal bool) error {
	// If we're running a full engine faking, accept any input as valid
	if cryptore.config.PowMode == ModeFullFake {
		return nil
	}
	// Short circuit if the header is known, or its parent not
	number := header.Number.Uint64()
	if chain.GetHeader(header.Hash(), number) != nil {
		return nil
	}
	parent := chain.GetHeader(header.ParentHash, number-1)
	if parent == nil {
		return consensus.ErrUnknownAncestor
	}
	// Sanity checks passed, do a proper verification
	return cryptore.verifyHeader(chain, header, parent, false, seal)
}

// VerifyHeaders is similar to VerifyHeader, but verifies a batch of headers
// concurrently. The method returns a quit channel to abort the operations and
// a results channel to retrieve the async verifications.
func (cryptore *Cryptore) VerifyHeaders(chain consensus.ChainHeaderReader, headers []*types.Header, seals []bool) (chan<- struct{}, <-chan error) {
	// If we're running a full engine faking, accept any input as valid
	if cryptore.config.PowMode == ModeFullFake || len(headers) == 0 {
		abort, results := make(chan struct{}), make(chan error, len(headers))
		for i := 0; i < len(headers); i++ {
			results <- nil
		}
		return abort, results
	}

	// Spawn as many workers as allowed threads
	workers := runtime.GOMAXPROCS(0)
	if len(headers) < workers {
		workers = len(headers)
	}

	// Create a task channel and spawn the verifiers
	var (
		inputs = make(chan int)
		done   = make(chan int, workers)
		errors = make([]error, len(headers))
		abort  = make(chan struct{})
	)
	for i := 0; i < workers; i++ {
		go func() {
			for index := range inputs {
				errors[index] = cryptore.verifyHeaderWorker(chain, headers, seals, index)
				done <- index
			}
		}()
	}

	errorsOut := make(chan error, len(headers))
	go func() {
		defer close(inputs)
		var (
			in, out = 0, 0
			checked = make([]bool, len(headers))
			inputs  = inputs
		)
		for {
			select {
			case inputs <- in:
				if in++; in == len(headers) {
					// Reached end of headers. Stop sending to workers.
					inputs = nil
				}
			case index := <-done:
				for checked[index] = true; checked[out]; out++ {
					errorsOut <- errors[out]
					if out == len(headers)-1 {
						return
					}
				}
			case <-abort:
				return
			}
		}
	}()
	return abort, errorsOut
}

func (cryptore *Cryptore) verifyHeaderWorker(chain consensus.ChainHeaderReader, headers []*types.Header, seals []bool, index int) error {
	var parent *types.Header
	if index == 0 {
		parent = chain.GetHeader(headers[0].ParentHash, headers[0].Number.Uint64()-1)
	} else if headers[index-1].Hash() == headers[index].ParentHash {
		parent = headers[index-1]
	}
	if parent == nil {
		return consensus.ErrUnknownAncestor
	}
	if chain.GetHeader(headers[index].Hash(), headers[index].Number.Uint64()) != nil {
		return nil // known block
	}
	return cryptore.verifyHeader(chain, headers[index], parent, false, seals[index])
}

// VerifyUncles verifies that the given block's uncles conform to the consensus
// rules of the stock Core cryptore engine.
func (cryptore *Cryptore) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
	// If we're running a full engine faking, accept any input as valid
	if cryptore.config.PowMode == ModeFullFake {
		return nil
	}
	// Verify that there are at most 2 uncles included in this block
	if len(block.Uncles()) > maxUncles {
		return errTooManyUncles
	}
	if len(block.Uncles()) == 0 {
		return nil
	}
	// Gather the set of past uncles and ancestors
	uncles, ancestors := mapset.NewSet(), make(map[common.Hash]*types.Header)

	number, parent := block.NumberU64()-1, block.ParentHash()
	for i := 0; i < 7; i++ {
		ancestor := chain.GetBlock(parent, number)
		if ancestor == nil {
			break
		}
		ancestors[ancestor.Hash()] = ancestor.Header()
		for _, uncle := range ancestor.Uncles() {
			uncles.Add(uncle.Hash())
		}
		parent, number = ancestor.ParentHash(), number-1
	}
	ancestors[block.Hash()] = block.Header()
	uncles.Add(block.Hash())

	// Verify each of the uncles that it's recent, but not an ancestor
	for _, uncle := range block.Uncles() {
		// Make sure every uncle is rewarded only once
		hash := uncle.Hash()
		if uncles.Contains(hash) {
			return errDuplicateUncle
		}
		uncles.Add(hash)

		// Make sure the uncle has a valid ancestry
		if ancestors[hash] != nil {
			return errUncleIsAncestor
		}
		if ancestors[uncle.ParentHash] == nil || uncle.ParentHash == block.ParentHash() {
			return errDanglingUncle
		}
		if err := cryptore.verifyHeader(chain, uncle, ancestors[uncle.ParentHash], true, true); err != nil {
			return err
		}
	}
	return nil
}

// verifyHeader checks whether a header conforms to the consensus rules of the
// stock Core cryptore engine.
// See YP section 4.3.4. "Block Header Validity"
func (cryptore *Cryptore) verifyHeader(chain consensus.ChainHeaderReader, header, parent *types.Header, uncle bool, seal bool) error {
	// Ensure that the header's extra-data section is of a reasonable size
	if uint64(len(header.Extra)) > params.MaximumExtraDataSize {
		return fmt.Errorf("extra-data too long: %d > %d", len(header.Extra), params.MaximumExtraDataSize)
	}
	// Verify the header's timestamp
	if !uncle {
		if header.Time > uint64(time.Now().Add(allowedFutureBlockTime).Unix()) {
			return consensus.ErrFutureBlock
		}
	}
	if header.Time <= parent.Time {
		return errOlderBlockTime
	}
	// Verify the block's difficulty based on its timestamp and parent's difficulty
	expected := cryptore.CalcDifficulty(chain, header.Time, parent)

	if expected.Cmp(header.Difficulty) != 0 {
		return fmt.Errorf("invalid difficulty: have %v, want %v", header.Difficulty, expected)
	}
	// Verify that the energy limit is <= 2^63-1
	cap := uint64(0x7fffffffffffffff)
	if header.EnergyLimit > cap {
		return fmt.Errorf("invalid energyLimit: have %v, max %v", header.EnergyLimit, cap)
	}
	// Verify that the energyUsed is <= energyLimit
	if header.EnergyUsed > header.EnergyLimit {
		return fmt.Errorf("invalid energyUsed: have %d, energyLimit %d", header.EnergyUsed, header.EnergyLimit)
	}

	// Verify that the energy limit remains within allowed bounds
	diff := int64(parent.EnergyLimit) - int64(header.EnergyLimit)
	if diff < 0 {
		diff *= -1
	}
	limit := parent.EnergyLimit / params.EnergyLimitBoundDivisor

	if uint64(diff) >= limit || header.EnergyLimit < params.MinEnergyLimit {
		return fmt.Errorf("invalid energy limit: have %d, want %d += %d", header.EnergyLimit, parent.EnergyLimit, limit)
	}
	// Verify that the block number is parent's +1
	if diff := new(big.Int).Sub(header.Number, parent.Number); diff.Cmp(big.NewInt(1)) != 0 {
		return consensus.ErrInvalidNumber
	}
	// Verify the engine specific seal securing the block
	if seal {
		if err := cryptore.VerifySeal(chain, header); err != nil {
			return err
		}
	}
	return nil
}

// CalcDifficulty is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time
// given the parent block's time and difficulty.
func (cryptore *Cryptore) CalcDifficulty(chain consensus.ChainHeaderReader, time uint64, parent *types.Header) *big.Int {
	return CalcDifficulty(chain.Config(), time, parent)
}

// CalcDifficulty is the difficulty adjustment algorithm. It returns
// the difficulty that a new block should have when created at time
// given the parent block's time and difficulty.
func CalcDifficulty(config *params.ChainConfig, time uint64, parent *types.Header) *big.Int {
	return calcDifficulty(time, parent)
}

// Some weird constants to avoid constant memory allocs for them.
var (
	expDiffPeriod = big.NewInt(100000)
	big1          = big.NewInt(1)
	big2          = big.NewInt(2)
	big5          = big.NewInt(5)
	bigMinus99    = big.NewInt(-99)
)

// makeDifficultyCalculator creates a difficultyCalculator.
// the difficulty is calculated with rules
func makeDifficultyCalculator() func(time uint64, parent *types.Header) *big.Int {
	// Note, the calculations below looks at the parent number, which is 1 below
	// the block number. Thus we remove one from the delay given
	return func(time uint64, parent *types.Header) *big.Int {
		// https://github.com/core/CIPs/issues/100.
		// algorithm:
		// diff = (parent_diff +
		//         (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
		//        ) + 2^(periodCount - 2)

		bigTime := new(big.Int).SetUint64(time)
		bigParentTime := new(big.Int).SetUint64(parent.Time)

		// holds intermediate values to make the algo easier to read & audit
		x := new(big.Int)
		y := new(big.Int)

		// (2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9
		x.Sub(bigTime, bigParentTime)
		x.Div(x, big5)
		if parent.UncleHash == types.EmptyUncleHash {
			x.Sub(big1, x)
		} else {
			x.Sub(big2, x)
		}
		// max((2 if len(parent_uncles) else 1) - (block_timestamp - parent_timestamp) // 9, -99)
		if x.Cmp(bigMinus99) < 0 {
			x.Set(bigMinus99)
		}
		// parent_diff + (parent_diff / 2048 * max((2 if len(parent.uncles) else 1) - ((timestamp - parent.timestamp) // 9), -99))
		y.Div(parent.Difficulty, params.DifficultyBoundDivisor)
		x.Mul(y, x)
		x.Add(parent.Difficulty, x)

		// minimum difficulty can ever be (before exponential factor)
		if x.Cmp(params.MinimumDifficulty) < 0 {
			x.Set(params.MinimumDifficulty)
		}
		return x
	}
}

// VerifySeal implements consensus.Engine, checking whether the given block satisfies
// the PoW difficulty requirements.
func (cryptore *Cryptore) VerifySeal(chain consensus.ChainHeaderReader, header *types.Header) error {
	return cryptore.verifySeal(chain, header)
}

// verifySeal checks whether a block satisfies the PoW difficulty requirements.
func (cryptore *Cryptore) verifySeal(chain consensus.ChainHeaderReader, header *types.Header) error {
	// If we're running a fake PoW, accept any seal as valid
	if cryptore.config.PowMode == ModeFake || cryptore.config.PowMode == ModeFullFake {
		time.Sleep(cryptore.fakeDelay)
		if cryptore.fakeFail == header.Number.Uint64() {
			return errInvalidPoW
		}
		return nil
	}
	// If we're running a shared PoW, delegate verification to it
	if cryptore.shared != nil {
		return cryptore.shared.verifySeal(chain, header)
	}
	// Ensure that we have a valid difficulty for the block
	if header.Difficulty.Sign() <= 0 {
		return errInvalidDifficulty
	}

	// Recompute PoW values
	var result []byte
	cryptore.sealVM.Add(1)
	result, err := randomy.RandomY(cryptore.randomYVM, cryptore.vmMutex, cryptore.SealHash(header).Bytes(), header.Nonce.Uint64())
	cryptore.sealVM.Done()
	if err != nil {
		return err
	}

	target := new(big.Int).Div(two256, header.Difficulty)
	if new(big.Int).SetBytes(result).Cmp(target) > 0 {
		return errInvalidPoW
	}
	return nil
}

// Prepare implements consensus.Engine, initializing the difficulty field of a
// header to conform to the cryptore protocol. The changes are done inline.
func (cryptore *Cryptore) Prepare(chain consensus.ChainHeaderReader, header *types.Header) error {
	parent := chain.GetHeader(header.ParentHash, header.Number.Uint64()-1)
	if parent == nil {
		return consensus.ErrUnknownAncestor
	}
	header.Difficulty = cryptore.CalcDifficulty(chain, header.Time, parent)
	return nil
}

// Finalize implements consensus.Engine, accumulating the block and uncle rewards,
// setting the final state on the header
func (cryptore *Cryptore) Finalize(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header) {
	// Accumulate any block and uncle rewards and commit the final state root
	accumulateRewards(state, header, uncles)
	header.Root = state.IntermediateRoot(true)
}

// FinalizeAndAssemble implements consensus.Engine, accumulating the block and
// uncle rewards, setting the final state and assembling the block.
func (cryptore *Cryptore) FinalizeAndAssemble(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
	// Accumulate any block and uncle rewards and commit the final state root
	accumulateRewards(state, header, uncles)
	header.Root = state.IntermediateRoot(true)

	// Header seems complete, assemble into a block and return
	return types.NewBlock(header, txs, uncles, receipts, new(trie.Trie)), nil
}

// SealHash returns the hash of a block prior to it being sealed.
func (cryptore *Cryptore) SealHash(header *types.Header) (hash common.Hash) {
	hasher := sha3.New256()

	rlp.Encode(hasher, []interface{}{
		header.ParentHash,
		header.UncleHash,
		header.Coinbase,
		header.Root,
		header.TxHash,
		header.ReceiptHash,
		header.Bloom,
		header.Difficulty,
		header.Number,
		header.EnergyLimit,
		header.EnergyUsed,
		header.Time,
		header.Extra,
	})
	hasher.Sum(hash[:0])
	return hash
}

// Some weird constants to avoid constant memory allocs for them.
var (
	big8  = big.NewInt(8)
	big32 = big.NewInt(32)
)

// AccumulateRewards credits the coinbase of the given block with the mining
// reward. The total reward consists of the static block reward and rewards for
// included uncles. The coinbase of each uncle block is also rewarded.
func accumulateRewards(state *state.StateDB, header *types.Header, uncles []*types.Header) {
	// Select the correct block reward based on chain progression
	blockReward := BlockReward
	// Accumulate the rewards for the miner and any included uncles
	reward := new(big.Int).Set(blockReward)
	r := new(big.Int)
	for _, uncle := range uncles {
		r.Add(uncle.Number, big8)
		r.Sub(r, header.Number)
		r.Mul(r, blockReward)
		r.Div(r, big8)
		state.AddBalance(uncle.Coinbase, r)

		r.Div(blockReward, big32)
		reward.Add(reward, r)
	}
	state.AddBalance(header.Coinbase, reward)
}